package cn.edu.neu;
//Duck fly       WildDuck
public class App {
    public static void main(String[] args) {
        WildDuck wildDuck = new WildDuck();
        wildDuck.fly();
    }
}
class Duck{ //父类：行为变化修改困难
    public void fly(){
        System.out.println("鸭子会飞。。。");
    }
}
class WildDuck extends Duck{ //子类WildDuck继承Duck

}

